The origin of the molecular "handedness" that pervades earth's biology has been an evolutionary puzzle. Given that right and left-handed amino acids have equal energies, why do only the left-handed ones participate in biosynthesis? One hypothesis is that life started from templates that arose from extraterrestrial sources, such as meteors. GC/MS analysis of the Murchison meteorite shows that it displays an excess of left-handed amino acids, in support of this idea. An important aspect of this research is that the excesses were found in amino acids that are not utilized in life on earth, so that it would seem unlikely that the enantiomeric excess was due to contamination. Science had a trial period in which they allowed non-subscribers to read the journal online, but that offer is no longer available. I believe that you will be able to read the summary in the hyperlink above, after a free "registration" at the journal Web site.
J. R. Cronin and S. Pizzarello